Are contact lens lifetimes based on time worn or time since opening the packet? I wear soft toric two-week lenses twice a week for sport, for about two hours each time. Since the lenses are rated for two weeks, that means four uses per lens, even though they could theoretically be worn eight hours a day, every day. Naturally, I'd like to wear the lenses for longer *cough cough* and sometimes do *cough cough*, since this seems rather wasteful and they work perfectly well after the two weeks are up. Is the lifetime based on how long they've been open or on how long they've been worn? If the latter, does it sound sensible to wear them a while longer?

Required notes: I'm diligent about cleaning the lenses, storing them in fresh solution, discarding them if they get damaged, and so on. YANAD, YANMD and I promise to take all guidance with a grain of salt and a healthy handful of common sense.

Focus group of one, IANYO: I wear my two-week lenses for three weeks, at least 12 hours a day, with (knock wood) no ill effect thus far. I do remove and clean every night and don't sleep in them. Given the short duration you're wearing yours, I'd say you could go at least a month, maybe more.posted by Sweetie Darling at 10:29 AM on January 13, 2014 [1 favorite]

I have the same problem, I only wear contacts on weekends or after work.

Personally I wouldn't risk it. I've found that my eyes get red, itchy, gunky after wearing lenses past the date. I wear my specific brand for 4 weeks before I toss them but YMMV.

Finally, try using clear care which not only clean but disinfects. Caution: this is NOT regular contact lens solution, once you put it in the container it needs 6-8h to fully disinfect, otherwise your eyes will burn up to holy heaven.posted by St. Peepsburg at 10:30 AM on January 13, 2014

(My lenses are specified as 4-week lenses though.)posted by St. Peepsburg at 10:32 AM on January 13, 2014

My understanding is that the lifetime is based on hours worn. Briefly, the contacts are semi air permeable. Over time, the pores that make the contacts semi air permeable are clogged by proteins from your eyeballs. Once the pores are clogged it is no longer healthy for your eyes to have the contacts in them for long times.posted by u2604ab at 10:33 AM on January 13, 2014

I treat the lifetime as time worn, not calendar days. I've let my eye doctor know this and she agreed that was fine. However if my eyes started getting red or extra dry sooner, I don't think twice about tossing them.posted by rhapsodie at 10:34 AM on January 13, 2014

I regularly wear lenses longer than they are rated for. Just switch them out when they start to get uncomfortable and you'll be fine. Two hours at a time is not going to hurt your eyes.posted by rabbitrabbit at 10:34 AM on January 13, 2014

When I got contacts again after a long period of just wearing glasses, the optometrist said that the lifetime is based on when the packets are opened. Specifically, he asked if I planned to wear them everyday (in which case he'd prescribe more expensive, monthly contacts with astigmatism correction) or only now and then (in which case he'd prescribe cheaper daily throw-aways without that correction), because the the more expensive ones would have the same lifespan whether or not I wore them. If you can do without the toric correction, you'd probably be better off with dailies for that reason.

I got the monthlies and do, however, wear them for roughly twice their prescribed lifespan before they start to bother me, so you could probably push your two weeks a bit.posted by Partial Law at 10:34 AM on January 13, 2014

As long as your eyes are comfortable, and your vision is good. Wear them until you start having problems.posted by Ruthless Bunny at 10:43 AM on January 13, 2014

My opthamologist, from whom I purchase my contacts, says since opening the packet. Another opthamologist, for whom I am a regular subject for industry-paid new-contact-lens-product-testing experiments, says it's about hours worn. I believe the guy who gains nothing from my contact lens purchases and who benefits from my vision remaining as it is.posted by headnsouth at 10:55 AM on January 13, 2014 [2 favorites]

My use pattern is more like 1.5 times a week and switching to dailies really improved my quality of life-no more fussing about with cleaning or solution, ever, the lenses always feel fresh and awesome, and the cost difference was totally negligible. I think my 120 pairs of dailies cost me about $150 and I'm still using them more than a year later. I don't remember how much the monthlies were that I used to use, but they can't have been that much less and the subjective experience of wearing them was so much worse-I remember loving the day when I got to put a new one in and now that day is every day.posted by Kwine at 11:03 AM on January 13, 2014

I have silicone toric lenses. They are monthly disposables. They are not available in daily disposables. If they were, I would use those.

The reason I use silicone lenses is because they let a lot of oxygen through, so I don't get cell death in my eyes (which I did with the ordinary soft lenses). You hardly ever wear your lenses, so I can't imagine cell death is likely to be a problem for you.

However, that doesn't mean it's a good idea to keep lenses indefinitely. Bacteria will still build up over time, even if the lenses seem good to see through. You can't be too careful with your eyes.

But yeah, disposables if you can get them. If you can't, I suggest trying to find out if you can manage without toric.posted by tel3path at 11:20 AM on January 13, 2014 [2 favorites]

Like many, I wear mine until they start bugging me (much more than 2 weeks, typically). However, I do find that even if I wear them very sporadically, they don't last That much longer. In your case, I'd feel free to wear them for awhile longer. Any and all eye professionals will tell you that you shouldn't wear them for the equivalent number of waking hours in two weeks, though. And they're undoubtedly right. Aim somewhere in the middle, and pay attention to how your eyes feel, and you'll be fine.posted by ldthomps at 11:53 AM on January 13, 2014

I have the same question, so thanks for posting. I've been following the idea to wear them 'til uncomfortable, which for me is 4-5 weeks with a lens marked as having a 2-week replacement schedule. These are the contacts I use, and you'll see under the details tab by the replacement schedule line, there's an “i” (for information). Clicking on that, it says that the two-week replacement schedule means “You’ll only need to change these soft, disposable contacts once a month.”

Odd, huh? It makes me more confused.posted by Leontine at 12:12 PM on January 13, 2014

I regularly wear my lenses longer than the suggested time - I usually change them every 4 weeks though they are rated for only 2 weeks.

I would suggest that you use Clear Care lens solution though - it does a great job of removing proteins. Also, if you're only wearing them 2 days a week then it might help to change the solution every couple of days if you haven't worn them.posted by barnoley at 12:34 PM on January 13, 2014

Nthing the Clear Care.

I have daily disposables, but I usually wear them for maybe a week or so per pair, often for long hours per day, cleaning them nightly with Clear Care and pitching them when they don't feel 100% comfy anymore. I have been doing this for years and years to no ill effect. Before my dailies I similarly expanded the time frame on 2-week lenses and monthly lenses, also with zero problems.posted by involution at 12:14 AM on January 14, 2014

My optometrist told me it's fine to just wear them till they feel uncomfortable. I think mine say a month on the box.posted by springbound at 6:22 AM on January 14, 2014

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